Electronic heads start at around £9, I have bought 5 and £15 each and they are designed to fit a range of bases, with mine there are 4 error codes, one clearly discharged battery, but also valve too sluggish, actuating range too wide (i.e. not fitted to a valve), actuating range too small (i.e. valve stuck), they also exercise the valve mid day every Saturday so less likely to stick, and you set temperature in °C not *123456 plus can set different temperatures at different times of day or week. I bought the Bluetooth version as hard to see screen when fitted horizontal, there are two cheap makes of electronic valve I have seen the Terrier i30 and the eqiva I bought the latter, who do a manual and bluetooth version. Note bluetooth will only work with one phone.
yes there are far better heads, clearly if boiler is not running when the temperature is scheduled to change, nothing happens, mine do have window open function so if it detects a sharp drop in temperature it will shut of for set time (default 15 minutes) so when I unload car into kitchen the heating turns off while I do it. It says batteries last 2 years, not had these long enough, but had the Energenie ones three years still on original batteries. OK they cost £40 a pop not £15.
However one has to ask, why replace heads with mechanical type, the electronic offer so much extra at such a small extra cost, can't see point in mechanical type.
this is where I got mine from but note the non Bluetooth are done in
Screwfix.
